The urinary excretion of the renal cortical enzyme kallikrein is abnormal in various human and animal hypertensive states, including essential hypertension. These findings, as well as the relationship between the renal kallikrein-kinin system and adrenal sodium-retaining steroid activity, suggest that this system could be involved in renal function and the control of systemic blood pressure. The proposed research will continue to determine if maneuvers or disease which alter adrenal-renal function and/or blood pressure affect the activity of components of the renal kallikrein-kinin system and conversely, if altered kallikrein or kinin activity affect renal function and blood pressure. Studies of the renal kallikrein-kinin system will continue in epidemiological surveys, clinical investigation, animal model experimentation and cellular biochemistry. Normal volunteers and patients with hypertensive diseases and hypertensive animal models will continue to be used. The objectives are: 1) to continue to define factors which influence kallikrein excretion in studies at different levels of biological organization; 2) to determine relationships between altered kallikrein excretion and the activity of the renal kallikrein-kinin system; and 3) to assess the role of this system in hypertensive disease states. BIBLIOGRAPHIC REFERENCES: Geller, R.G., H.S. Margolius, J.J. Pisano and H.R. Keiser: Effect of Altered Sodium Intake on Urinary Kallikrein Excretion in Spontaneously Hypertensive and Wistar-Kyoto Rats. Circ. Res., Suppl. I, 36: 103, 1975. Kass, E.H., H.S. Margolius and S.H. Zinner: Urinary Kallikrein and Blood Pressure in Childhood. In The Epidemiology and Control of Hypertension, Vol. II, O. Paul, ed., Stratton Medical Publishers, Miami, Fla., 1975.